Choppy Video Playback of iTunes TV Shows

I get choppy playback when trying to watch TV shows in full screen that I purchased on iTunes and downloaded to my PC. If I pop out the video player from iTunes and scale it down to a smaller window, the iTunes TV shows play seamlessly. But if I expand to full screen the shows get choppy.

I have an ASUS ROG gaming PC laptop with Intel Core i7-6700HQ cpu which has Intel® HD Graphics 530 and supports 4k resolution at 60hz. My monitor is an ASUS VP28UQG 28" 4K/UHD 3840x2160. I'm using a cord which connects to my mini display port on my laptop to the display port on the monitor so I do get 4k@60hz from the laptop to the monitor which is why I dont get lag/choppiness in other applications I watch movies and shows on (amazon, hbo, netflix).

My hard drive is a 7200rpm SATA drive (not SD) so thats the only hardware bottleneck I can think of. But the iTunes shows aren't even 4k, or 1080p. They're only 720p. So I don't see any reason why hardware would be an issue here.

I spent hours on the phone with the support team and they ended up directing me here so I'm really hoping someone here can help me diagnose this issue! Thanks!